[백준] 10828번 - 스택

문제 링크 : www.acmicpc.net/problem/10828

10828번: 스택

스택을 직접 구현하지 않아도 해결 가능하지만 구현해보았음

import sys

class Stack:
    def __init__(self):
        self.stack = []
        self.ptr = 0

    def push(self, data):
        self.stack.append(data)
        self.ptr += 1

    def pop(self):
        if self.ptr > 0:
            ret_value = self.stack[self.ptr - 1]
            del self.stack[self.ptr - 1]
            self.ptr -= 1

            return ret_value
        else:
            return -1

    def top(self):
        if self.ptr > 0:
            return self.stack[self.ptr - 1]
        else:
            return -1

    def size(self):
        return self.ptr

    def empty(self):
        if self.ptr > 0:
            return 0
        else:
            return 1


N = int(sys.stdin.readline())
stack = Stack()
for _ in range(N):
    op = sys.stdin.readline().strip().split()

    if 'push' == op[0]:
        data = int(op[1])
        stack.push(data)
    elif 'pop' == op[0]:
        print(stack.pop())
    elif 'size' == op[0]:
        print(stack.size())
    elif 'empty' == op[0]:
        print(stack.empty())
    elif 'top' == op[0]:
        print(stack.top())